Fountain pen with overflow chamber situated in the front part of the fountain pen body



May 10, 1960 T. Kovcs N FOUNTAIN PEN WITH ovERFLow CHAMBER SITUATED INTHE FRONT PART OF THE FOUNTAIN PEN BODY Filed April 1e, 195e UnitedStatesPatent" 2,935,969" y FOUNTAIN PEN WITH. OVERFLOW CHAMBER SITUATEDIN THE FRONT OE THE FOUNTAIN PEN BODY This invention relates.to'fountain pens having, an.over. flow -chamber situated" in the frontpart. of the fountain pen body which consists of at least onelongitudinally extending capillary space of annular cross sectionnarrowing towards the ink` reservoir and communicating .at the frontwith the atmosphere and at the rear through an. air passagewith the inkreservoir.

It is an object of the invention to improve the func.- tioning of theoverflow chamber formed by the capillary space or spaces by speciallydesigning said space or spaces. It is a special object of the inventionto control the processes of illing, and emptying of the overow chambermore accurately than has hitherto been possible.

It is another object ofthe invention to facilitate' the assembling ofthe fountain pen;

Other objects of the invention concern. details which will facilitatethe disassembling and reassembling for cleaning purposes of the partsessential for the proper functioningv of ther fountain pen.

The front part of a fountain pen according to the invention is shown atanY enlarged scale, and by way of example only, in the accompanyingdrawing in which:

Fig. 1 is a longitudinal' section of theA front part'of the fountain penin the'plane offsymmetry, and

Figs. 2, 3 and 4v are cross sectional views taken'along thecorresponding lines II-II, III-III, and IV-IVof Fig. l`. y

In the drawings, 1 designates thefont part of the hollow fountain penbody, in the rearwardly closed'frear part of which (not shown)risplocated the-inky reservoir. The bore of the. fountain pen body isrestricted at its front end 2. A tubular body 3* having ahead 4 isinserted inthe fountain .pen body. from. the: front.l so thatf onlyr itshead 4 projects outsideV said: body. The shank portion 5 of the tubularbody adjacent the head 4 is sealingly and` ixedly retained in the mouthof' the fountain pen body. TheV outside diameter ofthe rear end portion6 of the tubularl bodyis byr afew ten thousandths of an inch smallertharrthatof the shank portion 5, so that the rear end portion 6-mayreadily" be inserted through the mouthof the fountain-penbocly.' .Thetubular body has an intermediatepertion; ofaredilced diameter extending`between the shank portion 5 and the end portion 6. A short section 7 ofthe tubular body adjacent the end portion 6 has a diameter about .00Sin. (0.2 mm.) smaller than that of the end portion 6. The intermediateportion of the tubular body extending between the section 7 and theshank portion 5 is of a more reduced diameter and tapers from thesection 7 towards the shank portion 5 following the shape of a hyperbolaor of a hyperbolashaped curve. In the bore of the fountain pen body isinserted fro-m the rear a sleeve 9 which with its rear end 10 is xedlyretained in the bore of the fountain pen body. The sleeve 9 with itsfront end embraces the shank portion 5 and is thereby centered at thefront. Between its rear end portion 10 and its front end, the sleeve isof reduced outside diameter. A short section 11 of the sleeve adjacentthe rear end portion 10 has 2,935,969 Patented. May 10, 1960 2. anoutside diameter about` .008 in. (0.2 mm.) smaller than that of the endportion 10. The part' of the sleeve extending from section 11 to theVfront end thereof is of morer reduced diameter; The sleeve tapers in"longitudinall cross sectiontowards the front following the form of ahyperbola or of' a hyperbola-like curve. The section 7 of the tubularbo'dy 3 forms withinthe bore of sleeve 9 a space 12 of annular crosssection which is s'o narrow that,A during writing, it retains thequantity `of inle previously received therein. The capillary spaceformed within the bore of sleeve' 9 by the hyperboloid surface 8 of thetubular body 3 narrows in longitudinal cross section towardsthe inkreservoir, following the form of a hyperbola or of a hyperbola-likecurve, and is so di'rnensionedA as tobe capable of receiving excess inkand giving it olf again. The section 11 of sleeve 9 forms within thevbore of the fountain pen body a -space 14 correspondingtozthevnarrowspace 12,*while'the hyperboloid surface 15 of sleeve 9 forms an outerspace 16 corresponding tothe inner capillary space 13. Both spaces 13and 16 constitute the overow chamber.

The tubular body 3v is provided withv a through` bore thev innerdiameter of which is approximately .02 in. (0.5 mm.) greaterV within thehead 4 than behind said head. Insertedv from. the. front into the boreVof the tubular. body isa pin.17l having. a thickenedfrontr portion 18.which fits into the front. partoff the bore of the tubu-V lar. body andvis provided with. a recessadaptedv to receive the pen 19.' The reducedrear portion of the pin has an outside diameter which is by about .004in. (0I-l' mm.) smallerthan the diameter ofJ the surrounding.bore,.whereby a narrow space 20-of annular cross section fadapte'd to conduct inktherethrough is formed aroundithe reduced rear portion of the pin.

The head 4 of the tubular body 3 covers the penalmost up to its point.A11-axial vent passage ZInarrowing towards the rear and extendingupwardly into vthe region ofthe front portion of the capillary spaces13, 16 i'sY provided in the front part of pin 17. In itswider front.part the vent passageZl is provided with threads, while at-its rear end,it communicates with spaceA 13 through a narrow transverse bore 22 ofpin 1.7. and through a further transverse bore 23 formed in theitubul'ar body 3. The sleeve 9 surroundingthe tubular body is provided withthree transverse bores 24 equally spaced aroundv its. circumference,toneof said'bores beingaligned coaxially with the aligned transverse bores22 and 231 The tubular body 3 and the sleeve 9 are each provided withlsets lof three longitudinal grooves 25 o and 26. re.- spectively,equally spaced around their circumference. One. of the longitudinalgrooyes25 terminates at the front in the wide transverse bore 23,. whilethe longitudinal grooves 26 terminate in the. wide` transverse bores 24of sleeve 9. The longitudinalgrooves areof such width that they haveV alower capillary potential than the capillary spaces 13; `16,` wherebythe surfaces '8 andf'1`5 ofthe respective bodies 3, 9 forming thecapillary spaces 13, 16 are divided into longitudinal lands. On the penside of the fountain pen, the rear end portion 6 of the tubular body 3and the rear end portion of sleeve 9 are provided with respective narrowlongitudinal slots 27, 28 which when wet will not allow the passage ofair. An air passage 29 about .02 in. (0.5 mm.) wide and increasing indepth towards the ink reservoir, is provided in the rear end portion ofthe sleeve in the central plane of slot 2S. An integral ange 30presenting a recess 31 on the side opposite the pen, is arranged on thesleeve 9 about .08 in. (2 mm.) ahead of the section 11 thereof. At therear the longitudinal slots 25 of the tubular body terminate short ofthe section 7, while the longitudinal slots 26 terminate short of collar30.

The Vspace 16 communicating with the ink reservoir' through air passage29 narrows in cross section towards the pen side of the fountain pen,whilst the space 13 is of constant circumferential width. The space 16has a higher capillary. potential than thetspace'13, at least in itsrear part. Y f

` Fixed in the rear end of the ink conductor pin 17 is an air evacuatngtube 32 the bore 33 of which communicates with the space 16 via a shortaxial bore 34 of the pin, aligned, radial bores 35, 36, 37, and airpassage 29, and with the atmosphere via bores 24, 23, 22 and 21.

Therelative position of the ink conductor pin V17 inserted from thefront into the tubular body 3, and of the sleeve 9 inserted from therear into the bore of the fountain pen body, is assured by theconnection of both parts with the-tubular body. The position of pin 17is determined by a key 39 of the tubular body, while the position of thesleeve is determined by a key 38 engaging in a groove of thetubularbody.

The fountain pen according to the invention functions as follows: VThefountain'pen is lled by drawing in ink in the usual manner. Duringwriting, the ink flows from the ink reservoir through the ink conduit 20to the pen 19, while the replacement air normally passes through thevent passage 21, the overflow chamber, and the air passage 29, into theink reservoir. Any excess ink that may be present flows from the inkreservoir Va the longitudinal slots 27, 28, and the air passage 29, intothe overflow chamber, in which it advances from the rear towards thefront. During writing, ink is drawn from the ink reservoir via the inkconduit 20, whereby a negative pressure is created in the reservoirwhich prevents the excess ink in the overflow chamber from flowing backinto the reservoir. After the elimination of all excess ink, replacementair will normally enter the reservoir.

The longitudinal grooves 25, 26 assure complete lll ing of the spaces13, 16 forming the overllow'chamber, due to the fact that they have alower capillary potential than the said spaces and divide the spacesinto longitudinal lands from which, during the advance of the excessink, the air may readily escape through the longitudinal grooves notcovered with ink.

The longitudinally extending capillary spaces 13, 16 taper inlongitudinal cross section towards the ink reservoir following the formof a hyperbola or of a hyperbola-like curve. With a constant taper ofthe spaces towards the ink reservoir, the capillary potential in said vspaces is irregular, being lower in the region correspondingapproximately to the mediumheight of said spaces, than in the regionsabove and below thereof. This disadvantage s eliminated by the noveldesign of said spaces according to the invention, and the functioning ofthe overflow chamber is substantially improved.

The outer space 1-6 communicating with the ink reservoir through airpassage 29 possesses a higher capillary potential than the inner space13, at least in its rear portion, so that the spaces will ll and emptyin the desired sequence. The complete filling and emptying of the spacesis further assisted by the fact that the outer space communicating withthe reservoir through the air passage, narrows in transverse crosssection towards the pen side of the fountain pen, whilst the inner spaceis of constant circumferential width.

The air passage 29 connecting the overflow chamber with the inkreservoir increases in depth towards the latter. Consequently, thereplacement air will encounter the necessary resistance only in thenarrower front part of the passage, and will periodically block theupper `part of the passage only for shortest periods of time, wherebythe air passage may also act as an ink passage to the overow chamber. t

The vent passage 21 in the front portion of the ink conductor pin 17narrows towards the rear in order to permit the ink contained in saidvent passage from the filling operation may be used up without anincrease in ow intensity. Threads 21 provided in the wider front of thepassage retain the ink and conduct it by increased capillary effect intothe narrower rear part of the bore.

I claim:

1; A fountain pen, comprising a barrel formed with an ink reservoir inthe rearportion thereof, at least one sleeve arranged within the frontportion of said barrel, the surfaces of said sleeve and of said barreldefining therebetween at least one longitudinally extending capillaryannular overow ink storage space, said space tapering from the front tothe rear, said sleeve being formed with a plurality of continuousuninterrupted longitudinal grooves cut into the outer surface thereofand extending over a length intermediate and non-contiguous the endportions of said sleeve, said grooves having a lower capii? larypotential than said overflow ink storage space and said sleeve beingotherwise uncompartmented in a transverse direction.

2. A fountain pen as set forth in claim 1, said sleeve being formed withtransverse bores in the front part of said sleeve, said groovesterminating at their front ends at said bores.

3. A fountain pen as set forth in claim 2, including a flange integralwith said sleeve near the rear end thereof, said grooves terminating attheir rear ends at said flange.

4. A fountain pen as set forth in claim 2, wherein said capillaryannular space tapers substantially along a hyperbolic curve from thefront toward the rear of said pen.

References Cited in the le of this patent UNITED STATES PATENTS(Addition to No. 991,812)

